Favorite Schools

Favorite Teams

Possible tornado rips roof off in McMinnvilleSpencer Wriggelsworth survived a possible tornado touch down in McMinnville Thursday afternoon. He took shelter in the building's office near NE 11th Way and NE Alpine Ave. as the roof was ripped off and strong winds scattered sheet metal and debris for several blocks.

Then at 4:35 p.m., another funnel cloud touched down in McMinnville for several minutes. The tornado tore across town on a quarter-mile path from north/northwest to south/southeast. It ripped off roofs, threw debris at least 1,000 feet into the air and lifted a trailer over an 8-foot fence, but no one was hurt.

Shawn Weagle and Kevin Donofrio, two meteorologists with the National Weather Service in Portland, headed to McMinnville to assess the damage. What they saw and heard earned the twister an EF-1 rating -- that means it had wind speeds of 86 to 110 mph. By comparison, an EF-5 tornado packs winds in excess of 200 mph.

"As quickly as it came, it was gone," Donofrio said. "To issue a warning was almost impossible. But looking at the damage it's easy to see that people could have been injured or killed."

One of the first things he and Weagle saw was a piece of lumber sticking out of the top of a mobile home near Northeast Alpine Street. The large board not only pierced the roof, it smashed down through a bed and into the mobile home's floor.

View full sizeThe path of the tornado in McMinnville Thursday traveled from NNW to SSE, and traveled about 1/4 mile, officials said.National Weather Service

"It takes a pretty good wind to pick up a piece of wood and see it projected vertically into the structure," Donofrio said. "It was very heavy."

Both men carried binders with a list of 28 damage indicators, including types of structures and the varying degree of damage caused by particular wind speeds. The larger the degree of damage, the higher the wind speeds.

Near a warehouse at Northeast 12th Avenue and Northeast Alpine, the men saw a number of 250- to 300-pound metal trellises that had been tossed into the air.

Winds were powerful enough to tear a large trailer from a vehicle, lift into the air and toss it over an 8-foot high fence.

"The exact wind speeds are not always clear," Donofrio said. "Some of the damage was right on the cusp between EF-0 and EF-1. But in some places it was solidly an EF-1."

As important as the physical damage is in determining a tornado's strength, eyewitness accounts of the twister's power also play a big role. McMinnville residents told the men that debris flew into the air 1,000 feet or higher.

That no one was injured was due in part to the tornado's short touch-down time.

By Weagle and Donofrio's calculations, the twister was on the ground for about three minutes. Donofrio said most tornadoes that touch down in the Northwest don't typically present a hook-shaped echo on radar, and their short duration leads to a limited time to accurately determine the storm's rotation before it dissipates.

Information gathered by Weagle and Donofrio is being combined with weather station data, radar and satellite images, photographs and weather spotter reports for a final report --to help forecasters in the future predict and warn people that severe weather is on the way.